Electrons Make Shells, Photons Make Boxes: Unmasking Radiation Chemistry in Liquid-Phase Imaging.

Beam-induced chemistry in liquid-phase imaging is now recognized as a key factor in interpreting nanoscale redox processes, yet its consequences depend strongly on the irradiation modality, solvent chemistry, and reacting material system. Here, we compare how soft X-ray and electron irradiation redirect the same galvanic replacement reaction between Cu2O nanocubes and gold precursors. In this model system, soft X-ray irradiation generates an oxidizing environment that promotes Cu2O dissolution and hollow Au nanobox formation, whereas electron irradiation favors surface-confined Au deposition and Au@Cu2O core-shell architectures. Adjusting the solution chemistry during LC-TEM restores the hollowing pathway, showing that the local beam-induced chemical environment controls the balance between deposition and dissolution. These findings demonstrate that, in Cu2O-Au galvanic replacement, the imaging beam is not merely a passive probe, but can actively reshape the observed nanoscale reaction pathway.